create procedure sp_ChangePassword(
@par_username nchar(100),
@par_password nchar(100))
as 
begin
DECLARE @hashed_password varbinary(250)
SET @hashed_password = HashBytes('SHA1', @par_password)
UPDATE [user1] 
SET [user1].password= (@hashed_password) 
where user1.user1_name = @par_username
end